A device for cutting apertures in the wall of a plastic tube

ABSTRACT

A device for stamping apertures in the wall of a corrugated thermoplastic tube comprises a rotatable hollow nut for guiding the outer wall of the tube, and bits for stamping apertures in the tube without supporting the inner wall of the tube during stamping from outside. The bits are depressed in the plastic material by operating cams or by a guiding groove. Preferably the bits are effective in the area just besides the profiled end of the nut.

United States Patent Inventor Cornelis Van Zon Swolle. Netherlands Appl. No 756,237

Filed Aug. 29, 1968 Patented Sept. 14, I971 Assignee Wavin N. V.

Zwolle, Netherlands Priority Sept. 1, 1967 Netherlands 6712017 DEVICE FOR CUTTING APERTURES IN THE [56] References Cited UNITED STATES PATENTS 3,234,838 2/l966 Faull 83/637 X 345,365 7/l886 Cheswright 83/194 X 1,408,877 3/1922 Funk 83/350 X 2,374,301 4/1945 Olney 83/194 X 2,419,534 4/1947 Burleson 83/l94 2,423,791 7/1947 Nelson 83/l94 X 2,547,375 4/1951 Chemack.. 83/519 3,3 l6,787 5/1967 Lambro 83/194 X Primary Examiner-Andrew R. Juhasz Assistant Examiner-Leon Gilden Attorney-Waters, Roditi & Shwartz EQ T S TUBE ABSTRACT: A device for stamping apertures in the wall of a alms rawmg corrugated thermoplastic tube comprises a rotatable hollow US. Cl 83/358, nut for guiding the outer wall of the tube, and bits for stamping 83/423, 83/519, 214/338 apertures in the tube without supporting the inner wall of the Int. Cl 826d 5/16 tube during stamping from outside. The bits are depressed in Field of Search 831192, the plastic material by operating cams or by a guiding groove. 193, 194, 350, 355, 357, 513, 519, 628, L83; 18/2 Preferably the bits are effective in the area just besides the 1; 214/338 profiled end of the nut.

DEVICE FOR cuTrINo APERrurtEs IN THE A or A PLASTIC TUBE or apertures whereby special sawing devices are employed are known per se.

The kind of draining pipes obtained with the aid of these devices can only be made with difficulty by means of these complicated devices, but even so only at a rather high price.

It is an object of the invention to provide a device by which in a simple way apertures of the desired dimensions can be made in the hollows of a plastic tube, especially a corrugated tube, without employing complicated devices, which apertures contrary to the apertures obtained by sawing in the tube do not become filled up and consequently have a long life,

Such a device for providing apertures in the wall of a plastic tube especially a corrugated tube for draining purposes comprises a frame with guide means for guiding the plastic tube, punching means for making apertures being mounted for radial movement, and lying outside respectively inside the tube, means for depressing said punching means which are effective without supporting means for the punching means at the inner side or outer side of the tube.

By employing suitably shaped punching members, rectangular or other formed apertures are obtained at the desired locations which have a profile different from that which is nor mally obtained by means ofa saw.

According to an advantageous embodiment, the guide means for the plastic tube consists of a hollow rotatable nut, connected with at least one radially inwardly movable punch provided at its end with bits for blanking out parts of the tube wall, which can cooperate with operating cams provided on a stationary ring for actuating the punches.

According to another advantageous embodiment, the guide means for the plastic tube consists of a hollow rotatable nut, said nut carrying a disc provided with a noncircular groove, a projection connected with the stationary punch being capable of movement in this disc.

The various objects of the invention will be clear from the description which follows and from the drawings, in which:

FIG. 1 is a section through a device according to the invention;

FIG. 2 is a section taken on line 11-11 in FIG. 1;

FIG. 3 is a modified embodiment of the device according to the invention; and

FIG. 4 is a section taken on line IV--IV in FIG. 3.

Represented in FIGS. 1 and 2 is a device consisting of a frame 1 carrying a stationary ring 2 in which by means of a ball bearing 3 a rotatable nut 4 (driven by a nonrepresented motor) is secured which serves as a guide member for a relatively thin plastic tube 6 of thermoplastic, polyvinylchloride or polyethylene, being 0.2-0.6 mm. thick. The inner wall 5 ofthe nut 4 has a helical profile corresponding with that of a corrugated tube 6 to be worked as shown in FIG. 1. Fixedly secured on the rotatable nut 4 are punching means in the shape of a punch 8 provided with bits 7 and a head 9. Operating cams 10 on the stationary ring 2 actuate the punch 8 and drive the bits through the wall of the tube.

The device operates as follows. A corrugated tube 6 formed on a tube forming machine is guided in the profiled wall portion 5 of the rotatable nut 4. The rotatable nut is driven via gear wheels (not shown) by the tube forming machine, whereby a synchronous process is obtained. The nut 4 with punch 8, head 9 and punching members in the shape of bits 7 rotate until the head 9 encounters an operating cam 10 whereby the punch is depressed and the bits 7 are passed through an opening in the nut 4 and an aperture is punched in the wall of the tube. It is evident that the number of apertures provided in the wall of the tube is determined by the number of operating cams 10.

The bits 7 are advantageously disposed in such a way that they exclusively provide apertures in the hollows of the corrugated tube, which is readily obtained by the form of the cams.

The punch is springloaded by a spring 11 in order to ensure the return thereof after making an aperture.

It is very remarkable that apertures can be obtained without using an inner core for supporting the inner side of the tube during punching. This is apparently due to the support effect provided by wall portion 5 of nut 4.

Represented in the FIGS. 3 and 4 is a preferred embodiment in which likewise a frame 1 is provided and a rotatable nut 4 serves as a guide member for the tube. The inner wall 5 of the nut 4 has likewise a profiled surface corresponding with that of the corrugated tube to be treated. This nut is connected with a disc 13 provided with a noncircular groove 12. In this groove 12 a projection 14 connected with a stationary punch 8' can move. On rotation of the nut 4, the disc 13 will be taken along and consequently the projection 14 connected with the punch will also be guided in this groove 12. Owing to the noncircular shape of the groove 12 the punch is depressed at the location of the noncircular part 15 and the wall of the tube is perforated. As will be noted the profile of the nut 4 substantially ends before the working area of the bits 7.

It should be noted that in the process of punching, the rotatable nut should for a moment stop, but due to the speed (0,1 sec. or less) at which the punching operation is carried out, it appears that in practice this can be omitted.

According to the drawing the profile of the plastic tube is regular, but in certain cases, tubes having a regularly varying profile, e.g. the hollows of different depths alternating with tops of different heights, are preferred.

Iclaim:

l. A device for forming apertures in the wall of a continuous, helically corrugated plastic tube for draining purposes, said device comprising a frame, a hollow rotatable nut axially fixed in said frame and threadably engaged with said tube to guidably advance the tube through the frame as the nut rotates, punching means for making apertures in the tube, said punching means being mounted for radial movement on one side of the wall of the tube, said nut being in threadable engagement with the tube in the region of the punch means, and means associated with said nut for depressing said punching means in accordance with the rotation of said nut to form the apertures in the tube without supporting means for the punching means at the other side of the wall of the tube.

2. A device according to claim 1, wherein said punching means includes at least one radially inwardly movable punch slidably supported in said nut intermediate the ends thereof, said nut being provided at the inner end thereof with a bit for stamping out part of the tube wall to form said apertures, and a stationary ring with operating cam means thereon for actuating the punch.

3. A device according to claim 1, wherein said means for depressing said punching means comprising a disc rotatably secured to said nut and provided with a noncircular groove, and a projection connected with the punching means and displaceable in said noncircular groove during rotation of said nut to actuate the punching means as the nut and disc rotate.

4. A device according to claim 3 wherein said punching means comprises a plurality of radial punches slidably supported in said frame and arranged therein in circumferentially spaced relation, each punch including one of said projections which is engaged in the noncircular groove. 

1. A device for forming apertures in the wall of a continuous, helically corrugated plastic tube for draining purposes, said device comprising a frame, a hollow rotatable nut axially fixed in said frame and threadably engaged with said tube to guidably advance the tube through the frame as the nut rotates, punching means for making apertures in the tube, said punching means being mounted for radial movement on one side of the wall of the tube, said nut being in threadable engagement with the tube in the region of the punch means, and means associated with said nut for depressing said punching means in accordance with the rotation of said nut to form the apertures in the tube without supporting means for the punching means at the other side of the wall of the tube.
 2. A device according to claim 1, wherein said punching means includes at least one radially inwardly movable punch slidably supported in said nut intermediate the ends thereoF, said nut being provided at the inner end thereof with a bit for stamping out part of the tube wall to form said apertures, and a stationary ring with operating cam means thereon for actuating the punch.
 3. A device according to claim 1, wherein said means for depressing said punching means comprising a disc rotatably secured to said nut and provided with a noncircular groove, and a projection connected with the punching means and displaceable in said noncircular groove during rotation of said nut to actuate the punching means as the nut and disc rotate.
 4. A device according to claim 3 wherein said punching means comprises a plurality of radial punches slidably supported in said frame and arranged therein in circumferentially spaced relation, each punch including one of said projections which is engaged in the noncircular groove. 